Co-axial dual fluids metering system and methods

ABSTRACT

A metering system for a fuel atomizer includes a housing having a fuel inlet and an oxidizer inlet arranged coaxially, and an oxidizer metering device having a plurality of oxidizer channels, an oxidizer flow controller, and a fuel metering device. The oxidizer channels are spaced apart circumferentially in the housing and are arranged angled in at least one of a radially inward direction and a tangential direction to create a swirl of oxidizer flow in a mixing chamber of the fuel atomizer. The oxidizer flow controller is configured to control flow of oxidizer from the oxidizer inlet to the plurality of oxidizer channels. The fuel metering device is configured to control fuel flow from the fuel inlet to the mixing chamber.

TECHNICAL FIELD

The present disclosure is directed to fuel systems, and moreparticularly directed to metering of fuel delivery systems havingmultiple stages to enhance evaporation of the fuel.

BACKGROUND

Many types of devices have been developed over the years for the purposeof converting liquids into aerosols or fine droplets readily convertedinto a gas-phase. Many such devices have been developed, for example, toprepare fuel for use in internal combustion engines. To optimize fueloxidation within an engine's combustion chamber, the fuel must bevaporized, homogenized with air, and in a chemically-stoichiometricgas-phase mixture. Ideal fuel atomization and vaporization enables morecomplete combustion and consequent lower engine out pollution.

More specifically, relative to internal combustion engines,stoichiometry is a condition where the amount of oxygen required tocompletely burn a given amount of fuel is supplied in a homogeneousmixture resulting in optimally correct combustion with no residuesremaining from incomplete or inefficient oxidation. Ideally, the fuelshould be completely vaporized, intermixed with air, and homogenizedprior to ignition for proper oxidation. Non-vaporized fuel droplets donot ignite or combust completely in conventional internal and externalcombustion engines, which degrades fuel efficiency and increases engineout pollution.

Attempts to reduce or control emission byproducts by adjustingtemperature and pressure typically affects the NO_(x) byproduct. To meetemission standards, these residues must be dealt with, typicallyrequiring after treatment in a catalytic converter or a scrubber. Suchtreatment of these residues results in additional fuel costs to operatethe catalytic converter or scrubber and may require additional componentcosts as well as packaging and mass implications. Accordingly, anyreduction in engine out residuals resulting from incomplete combustionwould be economically and environmentally beneficial.

An engine running a closed loop in which λ=1 (e.g., when λ equals theratio of air/fuel ratio (AFR) divided by the stoichiometric air/fuelratio (AFR_(stoich)) is targeted will typically be operating at or nearstoichiometery. If the fuel is not completely vaporized, the enginemanagement system (EMS) will add extra fuel to ensure thatstoichiometery is reached as the oxygen sensor is monitoring excessoxygen in the exhaust. A reduction in efficiency caused by fuel notbeing completely vaporized results from extra fuel being added to ensurestoichiometery is achieved. Fuel energy is wasted and unnecessarypollution is created when the fuel is not completely vaporized. Thus, byfurther breaking down and more completely vaporizing the fuel-airmixture, better fuel efficiency may be available.

Many attempts have been made to alleviate the above-described problemswith respect to fuel vaporization and incomplete fuel combustion. Inautomobile engines, for example, inlet port or direct fuel injection hasalmost universally replaced carburetion for fuel delivery. Fuelinjectors spray fuel directly into the inlet port or cylinder of theengine and are controlled electronically. Injectors facilitate moreprecise metering and control of the amount of fuel delivered to eachcylinder independently relative to carburetion. This reduces oreliminates charge transport time facilitating optimal transientoperation. Nevertheless, the fuel droplet size of a fuel injector sprayis not optimal and there is little time for the fuel to mix with airprior to ignition.

Some types of fuel delivery systems require a source of compressed airto properly delivery fuel to the cylinder for combustion. The compressedair it typically provided by the engine or a compressor componentoperated by the engine.

A number of challenges exist for implementing fuel delivery systemswithin the IC engine. For example, space on engines is typically in highdemand and there is limited space available on the engine for mountinglarge pieces. Therefore, there is a need for concise packaging of a fueldelivery system. Further, performance of the engine may be influenced bythe distance fluids from the fuel delivery system are required to travelto reach the combustion chamber. Still further, the way in which fueland oxidizer are routed to and delivered through the fuel deliverysystem may create uneven distribution of flow through the fuel deliverysystem and consequently create non-uniform delivery of fuel to thecombustion chamber. Other challenges exist related to the amount ofenergy required to operate the fuel delivery system and the undesirablecreation of pressure drops for fluids passing through the fuel deliverysystem.

Opportunities exist for improving fuel delivery systems for engines.

SUMMARY

The principles described herein may address some of the above-describeddeficiencies and others. Specifically, some of the principles describedherein relate to liquid processor apparatuses and methods.

One aspect provides a metering system for a fuel atomizer. The meteringsystem includes a housing and an oxidizer metering device. The housingincludes a fuel inlet and an oxidizer inlet arranged coaxially. Theoxidizer metering device includes a plurality of oxidizer channels, aoxidizer flow controller, and a fuel metering device. The oxidizerchannels are spaced apart circumferentially in the housing and arearranged angled in at least one of a radially inward direction and atangential direction to create a swirl of oxidizer flow in a mixingchamber of the fuel atomizer. The oxidizer flow controller is configuredto control flow of oxidizer from the oxidizer inlet to the plurality ofoxidizer channels. The fuel metering device is configured to controlfuel flow from the fuel inlet to the mixing chamber.

The oxidizer flow controller may include a solenoid actuated member thatmoves axially between a closed position sealing the plurality ofoxidizer channels and an open position providing flow communicationbetween the oxidizer inlet and the plurality of oxidizer channels. Theoxidizer flow controller may include a plurality of pins that moveaxially between a closed position sealing the plurality of oxidizerchannels and an open position providing flow communication between theoxidizer inlet and the plurality of oxidizer channels.

The fuel metering device may include a solenoid valve. The fuel meteringdevice and oxidizer metering device may be arranged coaxially. The fuelmetering device may be positioned radially inward from the oxidizermetering device. The oxidizer channels are angled radially inward at anangle relative to a longitudinal axis of the metering system. Theoxidizer channels may be angled tangentially relative to a longitudinalaxis of the metering system. The plurality of oxidizer channels mayinclude at least 10 oxidizer channels.

Another aspect of the present disclosure relates to a method of meteringoxidizer and fuel for a fuel atomizer. The method includes providing amixing chamber, a nozzle, an oxidizer metering device and a fuelmetering device, wherein the oxidizer metering device includes aplurality of oxidizer channels and the oxidizer metering device isarranged co-axially with the fuel metering device. The method alsoincludes controlling oxidizer flow through the plurality of oxidizerchannels to the mixing chamber to create a flow of oxidizer into themixing chamber, controlling fuel flow to the mixing chamber with thefuel metering device to create a mixture of oxidizer and fuel in themixing chamber, and delivering the mixture out of the nozzle.

The oxidizer metering device may include a solenoid actuated member, andcontrolling oxidizer flow may include moving the solenoid actuatedmember axially relative to the plurality of oxidizer channels. Theoxidizer metering device may include a plurality of pins arrangedadjacent to the oxidizer channels, and controlling oxidizer flow mayinclude operating the plurality of pins relative to the plurality ofoxidizer channels. The fuel metering device may include a solenoidvalve, and controlling fuel flow may include operating the solenoidvalve. The oxidizer channels may be arranged circumferentially spacedapart. The oxidizer channels may be angled in at least one of a radialdirection and a tangential direction.

A further aspect of the present disclosure relates to a pre-combustionfuel mixing device, which includes a pre-combustion mixing chamber andfirst and second fluid metering devices. The first fluid metering deviceis configured to deliver a first fluid to the pre-combustion mixingchamber. The second fluid metering device is arranged coaxially with thefirst fluid metering device and configured to deliver a second fluid tothe pre-combustion mixing chamber. The second fluid metering deviceincludes an inlet fluid chamber arranged radially outward from the firstfluid metering device, a plurality of circumferentially spaced apartchannels extending from the inlet fluid chamber to the pre-combustionmixing chamber, and at least two supply ducts providing flow of thesecond fluid to the inlet fluid chamber.

The plurality of circumferentially spaced apart channels may be angledradially inward. The plurality of circumferentially spaced apartchannels may be arranged at a tangential angle. The second fluidmetering device may include at least one valve member positioned in theinlet fluid chamber to control flow of the second fluid into theplurality of circumferentially spaced apart channels. The at least twosupply ducts may include at least four supply ducts arranged at equallyspaced apart circumferential locations.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate certain embodiments discussed belowand are a part of the specification.

FIG. 1 is a perspective view of an example fuel delivery device inaccordance with the present disclosure.

FIG. 2 is another perspective view of the fuel delivery device of FIG.1.

FIG. 3A is an exploded perspective view of the fuel delivery device ofFIG. 1.

FIG. 3B is another exploded perspective view of the fuel delivery deviceof FIG. 1.

FIG. 4 is a cross-sectional view of the fuel delivery device of FIG. 1taken along cross-section indicators 4-4.

FIG. 5A is a perspective view of air flow components of the fueldelivery device of FIG. 1 in an open position.

FIG. 5B is a partial cutaway view of the components shown in FIG. 5A.

FIG. 6A is a perspective view of the flow of the air control componentsof FIG. 5A in a closed position.

FIG. 6B is a partial cutaway view of the components of FIG. 6A.

FIG. 7A is a perspective view of flow control components of anotherexample fuel delivery device in accordance with the present disclosurein an open position.

FIG. 7B shows the components of FIG. 7A in a closed position.

FIG. 8A shows an end view of distal components of the fuel deliverydevice with a single air inlet.

FIG. 8B shows resulting variable output flow with the single inletarrangement of FIG. 8A.

FIG. 9A shows an end view of distal components of the fuel deliverydevice of FIG. 1 with a plurality of air inlets.

FIG. 9B shows the even flow output resulting from the air inletarrangement of FIG. 9A.

FIGS. 10A-10E are cross-sectional views showing operation of the fueldelivery device at FIG. 1 to control fuel and air flow through the fueldelivery device.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical elements.

DETAILED DESCRIPTION

Illustrative embodiments and aspects are described below. It will, ofcourse, be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

The present disclosure is generally directed to fuel delivery systems,and more particularly relates to dual fluids delivery systems. The fueldelivery system, devices and methods disclosed herein provide balanced,equalized pressure and flow while providing improved precision insupplying the amount of fluid released through the fuel delivery devicefor each discharge of fuel.

Dual fluids metering and spray systems require unique fluid handling todeliver fluids efficiently, without significant energy loss, andeffectively to provide balanced and uniform distribution. Balanced anduniform distribution facilitates homogenous internal mixing andunbiased, evenly distributed spray delivery at the nozzle. Balanced anduniform distribution is achieved through coaxial introduction andtransport of fluids as provided by an optimized geometry and packaging,which is embodied in the examples disclosed herein.

The devices and systems described herein provide two metering solenoidsarranged coaxially with an inline or radial configuration. The centralsolenoid metering valve is generally intended for liquid fluids (e.g.,fuel) and the outer solenoid metering valve is generally intended forgaseous fluids (e.g., air or gas). One fluid is typically a propellantor a liquid, and the other fluid is typically an oxidant or gas (e.g.,air or inert gas). The term oxidant as used herein may beinterchangeable with the terms air or gas.

The central solenoid actuates to release fuel into a multi-physicsatomizer portion of the fuel delivery device, which may also be referredto generally as a mixing chamber. The outer solenoid actuates to open aplurality of radially spaced apart air inlet holes, which provide a flowof oxidizing gas (e.g., air) through the air inlet channels into themixing chamber to mix with the fuel. The solenoids may be electricallyconnected to a connector via, for example, a single connector with powersupply and excitation pins for both solenoids. Alternatively, thesolenoids may be electrically connected to a controller via separateconnectors associated with each solenoid.

While the two fluids controlled through the fuel delivery devicetypically are a gas and liquid, other combinations such as gas/gas andliquid/liquid are possible. Internal to the fuel delivery device, thegas may physically interact with the liquid to provide initial breakupand to drive the liquid through the outlet holes for final breakup intothe smallest possible particle size. The mixture of fuel and gas areintroduced to the engine via an intake port. Equally distributed flowwithin the mixing chamber of the fuel delivery device may be importantfor producing balance, homogenous mixing as well as an unbiased deliverythrough the plurality of outlet holes formed in a nozzle at a distal endof the fuel delivery device. The fuel delivery devices disclosed hereinmay provide equal distribution for physical introduction of the gas intoan air inlet chamber, which is positioned upstream of the air inletchannels, using at least two air supply ducts. The at least two airsupply ducts influence how air travels through the air inlet channelsand into the mixing chamber. The number of air supply ducts and thearrangement of air inlet channels coaxial with the fuel delivery intothe mixing chamber may facilitate uniform distribution of droplets inthe resulting spray plume formed as the fuel and air mixture is ejectedthrough the nozzle.

Another aspect of the present disclosure relates to the two fluids beingindividually metered through the fuel delivery device for mixing andatomizing. The liquid component may be injected into the mixing chamberdirectly onto a centrally fixed pedestal. Initial breakup of the liquidoccurs here and mixing with the gaseous component, which is introducedinto the mixing chamber via a plurality of coaxially, radially arrangedair inlet channels. The air inlet channels may be arranged for straight(e.g., axial) introduction of gaseous component in the mixing chamber.Alternatively, the air inlet channels may be arranged at an incline orangle, in either or both of a circumferentially angled direction (alsoreferred to as a tangential direction) and a radially angled direction.The angled orientation of the air inlet channels (also referred to asoxidizer or gas channels) may produce a vortex flow in the mixingchamber. The air flow through each of the air inlet channels ispreferably approximately the same speed, pressure and mass flow rate inorder to provide optimized mixing within the mixing chamber andproduction of a even spray distribution out of the fuel delivery devicenozzle. In order to achieve this consistent flow through the airchannels, the air supply at the entrance to each air inlet channel maybe provided with a volume of air that has substantially the same speed,pressure and mass flow rate.

The coaxial arrangement of the gaseous fluid entry into the air inletchamber, through the air inlet channels and into the mixing chamber ofthe fuel delivery device may provide improved balance and equalizationof pressure and flow, thereby resulting in a more homogenous mixture inthe mixing chamber. The homogenous mixture may facilitate some of thedroplet breakup mechanisms within the mixing chamber and as the fuel airmixture exits via a nozzle of the fuel delivery device. Additionally,equalized pressure and flow of the air may facilitate improved cleanoutof the mixing chamber in pre- and post-liquid (e.g., fuel) meteringevents. Further, the equalized distribution into and through the mixingchamber may provide improved unbiased flow at the nozzle outlet holes,thereby facilitating a more uniform spray plume as discussed above.

Referring now to FIGS. 1-4, an example fuel delivery device 10 havingthe oxidizer flow control described above is shown and described. Thefuel delivery device includes a housing assembly 12, a fuel plunger 14,a fuel spring 16, an air plunger 18, an air spring 20, a first solenoid22, a fuel filter 26, and a second solenoid 28. The first solenoid 22operates with the air spring 20 to move the air plunger 18 between openand closed positions. The second solenoid 28 operates with the fuelspring 16 to move the fuel plunger 14 between open and closed positions.The first solenoid 22 includes a bore 96 within which at least the airplunger 18 extends. The second solenoid 28 includes a bore 98 withinwhich at least the fuel plunger 14 extends. The fuel filter 26 includesa distal surface 100 against which a proximal surface of the air spring20 contacts as will be described in further detail below.

The housing assembly 12 is described with reference to FIGS. 11 and 12A.The housing assembly 12 includes a delivery tip 30 (also referred to asa nozzle), a lower mix housing 32, an upper mix housing 34, a fuel innerhousing 36, an air housing 38, a solenoid housing 40, and a coverhousing 42. The housing assembly 12 also includes first, second andthird o-rings 44, 46, 48.

The delivery tip 30 includes a mixing chamber 52. The upper mix housing34 includes a fuel aperture 54, a fuel cavity 56, a plurality of airchannels 58, an air sealing seat 60, and an air aperture 62. The fuelinner housing 36 includes a plunger seat 64 and a fuel aperture 66. Theair housing 38 includes an air cavity 68 and a plurality of air inlets70. The solenoid housing 40 includes a first solenoid seat 72, an airspring seat 76, and a second solenoid seat 78. The cover housing 42includes a bore 80 sized to receive the fuel filter 26.

The fuel plunger 14 includes a distal sealing surface 82, an axial fuelchannel 84, a lateral fuel channel 86 and a spring seat 88. The airplunger 18 includes a distal sealing surface 90, a plunger bore 92, anda proximal surface 94. The air plunger 18 may be referred to as a valvemember.

The distal sealing surface 82 of the fuel plunger 14 is arranged tocontact the plunger seat 64 of the fuel inner housing 36 and to controlfluid flow from a fuel cavity 56 within the fuel inner housing 36 intothe mixing chamber 52. The distal sealing surface 90 of the air plunger18 is arranged to contact the air sealing seat 60 of the upper mixhousing 34 to control airflow from the air cavity 68 into the mixingchamber 52. The fuel inner housing 36 and fuel plunger 14 move axiallyin a direction independent of axial movement of the air plunger 18. Thisindependent movement may make it possible to move the fuel plunger 14and air plunger 18 in any desired sequence to control the flow of airand fuel into the mixing chamber 52. Further, the independent controlprovided by the embodiment of FIGS. 1-4 may make it easier to controlthe delays between opening and closing the fuel plunger 14 and airplunger 18. The air plunger 18 of fuel delivery device 10 may requireexchange of the fuel and air springs or changing the fuel and airpressures in order to change the delay between the opening and closingof each of the fuel and air plungers.

Various bulk air supplied geometries may provide control of air flowfrom the air cavity 68 into the air aperture 62. Air may be deliveredinto the air cavity 68 using, for example, at least one channel, amanifold, a rail, or similar common supply that delivers air through theair inlet into the air cavity 68. In some arrangements, the air may bedelivered to the air cavity 68 using a plurality of channels as will bediscussed in further detail below.

The air plunger 18 (also referred to as an oxidizer flow controller) maybe operable to provide concurrently a substantially uniform flow ofcompressed air to each of the air apertures 62. Air enters the aircavity 68 via the air inlets 70. The air is supplied via, for example, achannel, manifold or rail. The air may deadhead at an opposite side ofthe air cavity 68 (e.g., against an outer surface of the air plunger18). The air fills the air cavity 68 with an equalized pressure. Movingthe air plunger 18 away from the air sealing seat 60 of the upper mixhousing 34 exposes the air apertures 62 to the supply of equalizedpressure air.

FIG. 5A shows the air plunger 18 moved axially away from the upper mixhousing 34 such that the distal sealing surface 90 of the air plunger 18is spaced apart from the air sealing seat 60 to permit exposure of theair aperture 62 to the supply of equalized pressure air. FIG. 5B shows apartial cutaway view of the assembly shown in FIG. 5A. The air aperture62, when exposed to the pressurized air in the air cavity 68, provides aflow path for air to travel into the mixing chamber 52. FIG. 5B alsoshows the angled orientation of the air channels from the air aperture62 to the mixing chamber 52. The air channel 58 may be angledcircumferentially moving from the air aperture 62 to the mixing chamber52. In at least some arrangements, the air channel 58 may be angledradially inward or radially outward from the air aperture 62 to themixing chamber 52. The air channels 58 may be angled in bothcircumferential and radial directions.

FIG. 6A shows the air plunger 18 advanced axially to contact the distalsealing surface 90 against the air sealing seat 60. This orientation ofthe air plunger 18 seals the air aperture 62 from the source ofequalized pressure air held in the air cavity 68. FIG. 6B shows apartial cutaway view of the arrangement of FIG. 6A showing the interfacebetween the distal sealing surface 90 and the air sealing seat 60.

FIGS. 7A and 7B show an alternative embodiment for control of air flowinto the air aperture 62. FIG. 7A shows an air plunger 118 comprising ahousing 190 having a plurality of pintles 192 mounted thereto. Thepintles 192 (also referred to as pins 192) are arranged in alignmentwith each of the air apertures 62. The pintles 192 provide individualcontrol of air flow into the air aperture 62 and consequently throughthe air channel 58 to the mixing chamber 52.

In operation, the air plunger 118 moves axially away from the upper mixhousing 32 to expose the air apertures 62 to a volume of equalizedpressure air held in the air cavity 68 (see FIG. 7A). Air flow into themixing chamber 52 is stopped by advancing the air plunger 118 to seatthe pintles 192 in sealing engagement with the air apertures 62 as shownin FIG. 7B.

When a fluid (e.g., gas) enters into the air cavity 68 upstream of theair channels 58, it is important that the mass flow of the fluid isevenly distributed across the face of the air apertures 62. Fluidmetered externally and entering in at only one side of the air cavity 68typically biases the output into the air aperture 62 to one side of thefuel delivery device 10.

FIG. 8A shows an end view of the assembly of FIG. 5A with the airplunger 18 removed and only a single air inlet 70A into the air cavity68. The reference numbers in each of the air aperture 62 provides anexample of the flow variants from an average value. The variation in thenumber in each air aperture 62 shows the substantial bias in mass flowinduced when only a single air inlet 70A is used. This mass flow biasmay exhibit itself in a spray plume density variation or variations indroplet size (e.g., Saunter mean diameter (SMD)) and distribution of thespray plume. Consequently, the overall performance of the fuel deliverydevice may be negatively influenced when using only a single air inlet70A.

FIG. 8B shows output from the delivery tip 30 when using a single airinlet 70A. The output includes some streams having a lower flow rate F₁than the flow rate F₂ at other outlets of the delivery tip 30.

FIG. 9A shows the use of a plurality of air inlets 70A-70D into the aircavity 68 to which the air apertures 62 are exposed. The referencenumbers shown in the air aperture 62 represent a flow variance fromaverage value. A comparison of FIGS. 8A and 9A show that the variationis significantly reduced among all of the air aperture 62 when aplurality of air inlet 70A-70D are used. FIG. 9B shows the output atdelivery tip 30 as a result of the plurality of air inlets 70A-70D. Theoutput shown in FIG. 9B includes a consistent or even flow F₃ at all orsubstantially all of the outlets of delivery tip 30.

The use of a plurality of air inlets into the air cavity 68 may providea more robust approach as compared to a single air inlet, particularlywhen using a supply bulk such as the air plunger 18, which concurrentlyexposes all of the air apertures 62 to an equalized pressure air supply.The arrangement of fuel delivery device 10, which is at least in partrepresented by the schematic illustration of FIG. 9A, may provide bulkair supply to the fuel delivery device 10 and use a single solenoid toexpose all of the air aperture 62 as if they were exposed directly to abulk air chamber, channel or rail to provide air flow through the airinlets 70 to the air cavity 68. Supplying metered air to the air cavity68 at two or more points may provide an improved equalization of massflow into the air apertures 62 to insure a more balanced mass flowthrough the air channel 58 to the mixing chamber 52. Multiple meteredsupply points may be added to further balance flow into the air cavity68.

Referring again to FIGS. 1 and 2, the air inlet 70 in the air housing 38may be equally spaced apart around a periphery of the air housing 38.Typically, the air inlets 70 are arranged in pairs at 180° spacingaround the periphery of the air housing 38. The number of air inlets 70is typically an even number. However, different numbers and arrangementsare possible for the air inlet 70 in other embodiments.

The examples shown with reference to FIGS. 6A-7B operate to providecontrol of air flow through air aperture 62 using linear motion in anaxial direction. Other devices are possible with different types ofmotion including, for example, sliding motion in a directionperpendicular to a longitudinal axis of the fuel delivery device 10, androtational motion of, for example, the air plunger 18 relative to theupper mix housing 34.

Referring now to FIGS. 10A-10E, an example fuel delivery sequence orfueling event is described. FIG. 10A shows the fuel plunger 14 and airplunger 18 in closed positions. The fuel spring 16 applies a biasingforce to the fuel plunger 14 that holds the distal sealing surface 82against the plunger seat 64 to prevent fluid flow into the mixingchamber 52. The air spring 20 applies a biasing force to the air plunger18 to hold the distal sealing surface 90 against the air sealing seat60, which prevents airflow into the mixing chamber 52.

The fueling sequence is initiated by activating the first solenoid 22,which generates a magnetic field that draws the air plunger 18 rearwardagainst biasing forces of the air spring 20 to move the distal sealingsurface 90 away from the air sealing seat 60. Air from the air cavity 68travels through the air channels 58, into the mixing chamber 52, and outof the delivery tip 30. The air spring 20 is at least partiallycompressed when the air plunger 18 is retracted into the position shownin FIG. 10B.

A further step in the fueling sequence may include activating the secondsolenoid 28, which creates a magnetic field that draws the fuel plunger14 axially in a rearward direction against biasing forces of the fuelspring 16. Withdrawing the fuel plunger 14 as shown in FIG. 10C movesthe distal sealing surface 82 away from the plunger seat 64 to permitfuel to flow from the fuel cavity 56, through the fuel aperture 66 andfuel aperture 54, and into the mixing chamber 52 to mix with theairflow. The fuel and air mix within the mixing chamber 52 and aredelivered out of the delivery tip 30 for combustion within a combustionchamber of the IC engine.

The second solenoid 28 is then deactivated to eliminate the magneticfield acting upon the fuel plunger 14. With the magnetic field removed,the fuel spring 16 applies its biasing force to the fuel plunger 14 tobegin advancing the distal sealing surface 82 toward contact with theplunger seat 64 to stop fuel flow into the mixing chamber 52, as shownin FIG. 10D.

The airflow is stopped by deactivating the first solenoid 22, whicheliminates the magnetic field acting on air plunger 18 and permits theair spring 20 to advance the distal sealing surface 90 of the airplunger 18 into contact with the air sealing seat 60 as shown in FIG.10E. As discussed above, the delay between closing the fuel plunger 14and closing the air plunger 18 permits the air flow to clear out fuelwithin the mixing chamber 52 and delivery tip 30. The equalized flow ofair through the fuel delivery device 10 provided by the co-axialarrangement of air and fuel material features may provide improved clearout of fuel within the mixing chamber 52 and delivery tip 30.

The preceding description has been presented only to illustrate anddescribe certain aspects, embodiments, and examples of the principlesclaimed below. It is not intended to be exhaustive or to limit thedescribed principles to any precise form disclosed. Many modificationsand variations are possible in light of the above disclosure. Suchmodifications are contemplated by the inventor and within the scope ofthe claims. The scope of the principles described is defined by thefollowing claims.

What is claimed is:
 1. A metering system for a fuel atomizer,comprising: a housing having a fuel inlet and an oxidizer inlet arrangedcoaxially; an oxidizer metering device comprising: a plurality ofoxidizer channels spaced apart circumferentially in the housing, theoxidizer channels being angled in at least one of a radially inwarddirection and a tangential direction to create a swirl of oxidizer flowin a mixing chamber of the fuel atomizer; an oxidizer flow controllerconfigured to control flow of oxidizer from the oxidizer inlet to theplurality of oxidizer channels; a fuel metering device configured tocontrol fuel flow from the fuel inlet to the mixing chamber.
 2. Themetering system of claim 1, wherein the oxidizer flow controllercomprises a solenoid actuated member that moves axially between a closedposition sealing the plurality of oxidizer channels and an open positionproviding flow communication between the oxidizer inlet and theplurality of oxidizer channels.
 3. The metering system of claim 1,wherein the oxidizer flow controller comprises a plurality of pins thatmove axially between a closed position sealing the plurality of oxidizerchannels and an open position providing flow communication between theoxidizer inlet and the plurality of oxidizer channels.
 4. The meteringsystem of claim 1, wherein the fuel metering device comprises a solenoidvalve.
 5. The metering system of claim 1, wherein the fuel meteringdevice and oxidizer metering device are arranged coaxially.
 6. Themetering system of claim 5, wherein the fuel metering device ispositioned radially inward from the oxidizer metering device.
 7. Themetering system of claim 1, wherein the oxidizer channels are angledradially inward at an angle relative to a longitudinal axis of themetering system.
 8. The metering system of claim 1, wherein the oxidizerchannels are angled tangentially relative to a longitudinal axis of themetering system.
 9. The metering system of claim 1, wherein theplurality of oxidizer channels comprises at least 10 oxidizer channels.10. A method of metering oxidizer and fuel for a fuel atomizer,comprising: providing a mixing chamber, a nozzle, an oxidizer meteringdevice and a fuel metering device, the oxidizer metering devicecomprising a plurality of oxidizer channels, the oxidizer meteringdevice being arranged co-axially with the fuel metering device;controlling oxidizer flow through the plurality of oxidizer channels tothe mixing chamber to create a flow of oxidizer into the mixing chamber;controlling fuel flow to the mixing chamber with the fuel meteringdevice to create a mixture of oxidizer and fuel in the mixing chamber;delivering the mixture out of the nozzle.
 11. The method of claim 10,wherein the oxidizer metering device includes a solenoid actuatedmember, and controlling oxidizer flow includes moving the solenoidactuated member axially relative to the plurality of oxidizer channels.12. The method of claim 10, wherein the oxidizer metering deviceincludes a plurality of pins arranged adjacent to the oxidizer channels,and controlling oxidizer flow includes operating the plurality of pinsrelative to the plurality of oxidizer channels.
 13. The method of claim10, wherein the fuel metering device includes a solenoid valve, andcontrolling fuel flow includes operating the solenoid valve.
 14. Themethod of claim 10, wherein the oxidizer channels are arrangedcircumferentially spaced apart.
 15. The method of claim 10, wherein theoxidizer channels are angled in at least one of a radial direction and atangential direction.
 16. A pre-combustion fuel mixing device,comprising: a pre-combustion mixing chamber; a first fluid meteringdevice configured to deliver a first fluid to the pre-combustion mixingchamber; a second fluid metering device arranged coaxially with thefirst fluid metering device and configured to deliver a second fluid tothe pre-combustion mixing chamber, the second fluid metering devicecomprising: an inlet fluid chamber arranged radially outward from thefirst fluid metering device; a plurality of circumferentially spacedapart channels extending from the inlet fluid chamber to thepre-combustion mixing chamber; at least two supply ducts providing flowof the second fluid to the inlet fluid chamber.
 17. The pre-combustionfuel mixing device of claim 16, wherein the plurality ofcircumferentially spaced apart channels are angled radially inward. 18.The pre-combustion fuel mixing device of claim 16, wherein the pluralityof circumferentially spaced apart channels are arranged at a tangentialangle.
 19. The pre-combustion fuel mixing device of claim 16, whereinthe second fluid metering device includes at least one valve memberpositioned in the inlet fluid chamber to control flow of the secondfluid into the plurality of circumferentially spaced apart channels. 20.The pre-combustion fuel mixing device of claim 16, wherein the at leasttwo supply ducts include at least four supply ducts arranged at equallyspaced apart circumferential locations.